Ceramic coated muffler with drainage openings



March 28, 1967 W. H. POWERS CERAMIC COATED MUFFLER WITH DRAINAGEOPENINGS Original Filed Oct. 28, 1960 3 SheetS-Sheet l dao I N VEN TOR.

March 28, 1967 W. H. POWERS 3,311,189

CERAMIC COATED MUFFLER WITH DRAINAGE OPENINGS 'Original Filed Oct. 28,1960 5 Sheets-Sheet 2 INVENTOR. E' 5 'M/4247 70z0c715' March 28, 1967 w.H. POWERS 3,311,189

' CERAMIC COATED MUFFLER WITH DRAINAGE OPENINGS original Filed oct. 2S.`1960 3 Sheets-sheet s mii-- .El ELL-2. @l

ual parts or subassemblies.

United States Patent O 3,311,189 CERAMIC COATED MUFFLER WITH DRAINAGEOPENINGS Walter H. Powers, Racine, Wis., assignor to WalkerManufacturing Company, a corporation of Delaware Original applicationOct. 28, 1960, Ser. No. 65,767, now Patent No. 3,082,841, dated Mar. 26,1963. Divided and this application Dec. 4, 1962, Ser. No. 242,305 4Claims. (Cl. 181-35) This application is a division of my priorapplication Ser. No. 65,767, led Oct. 28, 1960, now Patent No.3,082,841, issued Mar. 26, 1963.

, My invention relates to mufers of the type used to silence'the exhaustof internal combustion engines.

It is the object of my invention to greatly reduce or eliminate thecorrosion of exhaust mufllers.

In accomplishing the object of my invention I co-at the surfaces of themuier with an anti-corrosive ceramic material of a type available on theopen market and which can be app-lied to a steel surface. I have foundthat it is `best to coaty the muffler surfaces after assembly ratherthan to try to coat-the surfaces of individ- Thus, I contemplate the dipcoating ofthe muier in an anti-corrosive ceramic slip. My inventionprovides a mutller construction that can be successfully coated withceramic by the dipping process or by other processes if desired.

The conventional muler contains a series of internal chambers within anouter shell. These form many internal pockets that interfere with theproper drainage of liquids and gases during the coating process.Improper. drainage at various stages of the ceramic coating process isvery likely to result in incomplete surface coverage and probably insubsequent rust-out at the uncovered areas.

Thus, a' further `object of my invention is to provide f a mul-lierconstruction with means for external and internal drainage so that itcan be properly ceramic coated.

The invention provides for proper drainage by means of holes located atthe correct positions in the various internal chambers. These arelocated and sized so that they do not have an adverse acoustic effect.

My invention is illustrated in the accompanying drawings in which:

FIGURE 1 is a side elevation, somewhat diagrammatic, showing the muffler1 in position for dipping in a bath of suitable corrosion resistingceramic;

FIG. 2 is a longitudinal cross-section through a typical muiller thatmay be dip coated in accordance with the principles of this invention;

FIG. 3 is an end elevation taken from the left of FIG. 2;

FIG. 4 is an end elevation taken from the right of FIG. 2;

FIG. 5 is a cross-section taken along the line 5-5 of FIG. 2;

FIG. 5A is a cross-section showing a modified form of partition that iscut off to provide air and liquid escape holes;

FIG. 6 is a cross-section taken along the line 6-6 of FIG. 4;

FIG. 7 is a cross-section through the plug of FIG. 6 prior to insertion;

FIG. 8 is a section similar to that of FIG. 6 showing a modified form ofplug;

FIG. 9 is a view taken from the right of FIG. 8;

, FIG. 10 is a section similar to that of FIGS with still another formof plug;

FIG. 11 is a view similar to that of FIG. 9 taken from the right of FIG.10;

ice

FIG. 12 is a side elevation of the plug of FIGS. 10 and l1; and

FIG. 13 is a side elevation of the plug of FIGS. 10- 12.

FIG. 1 illustrates dip ceramic coating of a carbon steel muier 1A.- Theceramic is in the form of a suitable slip or bath 3 contained in asuitable tank 5. The muiiler 1 may vbe suspended :by a hook 7 whichprovides the means for lowering the muffler down into the bath and afterall surfaces, internal and external, have been coated, for removing themuffler from the bath 3.

FIG. 2 is a longitudinal cross-section through a typical muffler 1. Itdiffers slightly from the muier I1A illustrated in FIG. l in that itshows a layer of asbestos 9 wrapped around the muffler casing 11 andheld in place by yan external layer of sheet metal 13. In the coatingprocess I prefer to omit the asbestos layer 9 and the sheet metal 13since the asbestos 9 will tend to soak up the various liquids involvedand the material so a-bsorbed may create diicu'lties in the subsequentcoating and firing of the ceramic dipped muier. l

The muiler 1 has a casing 11 which is formed of sheet steel (as are theinternal parts) that is rolled into an oval shape and the overlappingedges spot-welded together or lock-seamed in accordance with standardpractice. In the form shown in FIG. 2, the lock-seams would be 4alongthe `bottom edge of the shell 11. The opposite ends of the casing 11 areclosed by the headers 15 and 17. The outer peripheries of the headersare tightly connected to the end of the casing 11 in interlocked joints19 and 20 and in accordance with 4the invention the top sides of thejoints 19 and 20 (opposite the shell joint) are bent inwardly ordownwardly so that the outer surface of the casing 11 is exposed at eachend, thus enabling the outer shell 13 to be formed as a sheet andwrapped around the layer of asbestos 9 and then lock-seamed bylock-seaming equipment which passes over the flat @bent-in portions 20after the mutiiler 1A has been coated and red.

The silencingL structure within the muffler shell 11 is typical ofvarious types that can be used and will illustrate how such structureshould be adapted for the application of protective coatings presentingthe same problems as a dip ceramic coating. Thus, the interior of thecasing 11 is divided into a series of -longitudinally separated chambers.21, 23, 25, 27, and 29 by a series of transverse sheet steel partitions31, 33, 35, and 37.

` Each of the transverse partitions has, in accordance with the usualpractice, an annular flange around its outer periphery and this isspot-welded to the casing 11. Gas

, enters the casing 1|1 through an inlet bushing 39 which is supportedin and spot-welded to a neck 41 lformed in the inlet header 15. Theinner end of the bushing 39 is necked-down or reduced in diameter at 44and is supported in and spot-welded to a neck 45 in the partition 31.The extreme inner end of the bushing 39 has a slit or slotted Hare 47 tofacilitate the insertion of the end of an inlet conduit 49, such conduitbeing slipped inside of the reduced end 44 of bushing 39 at assemblywhen it and the associated parts to be described are inserted inside ofthe shell 11. The conduit 49 is supported in and spot-welded to flangednecks 51 and 53 of the partitions 33 and 35, respectively. A pair ofsets of louvers 55 Within the walls of the conduit 49 permits soundwaves to enter spit chamibers 57 that are formed around the conduit bymeans of a pancake-type charn- :ber-forming construction 59 consistingof complemental stamped halves that have ilanges that are spot-Weldedtogether and necks which are spot-Welded to the conduit 49, suchconstruction -being more fully described in my copending application,Serial No. 575,404, iiled Apr.

Gases leaving the inlet conduit 49 enter the chamber 27 and reverse Athedirection of llow to go back toward the inlet end of the muffler. Indoing this, the gases ow back through the Volume of the chamber 25between the partitions 33 and 35. These partitions have a series ofrelatively large openings 61 formed in them so that the gases can flowfreely and Without restricv tion from the chamber 27 to the chamber 23.Gases in the chamber 23 flow toward the out-let header 17 through anoutlet conduit 63 which is supported in and spot-welded to necks 65 and67 formed respectively in the partitions 33 and 35. The section of thetube 63 within chamber Z may be provided with louvers 69 opening intothe chamlber 25. The outer end of the outlet tube 63 is slidably fittedin and supported in the inner reduced end 71 of the outlet bushing 73which is expanded and spot-welded to the neck 75 in the outlet header17. The inner end 71 of the bushing 73 is slit and flared slightly at 77to enable it to be slipped over vthe end of the tube 63 and is alsospot-welded to the neck 79 in the partition 37. The slits in flares 77and 47 facilitate ceramic drainage as will be self-evident hereinafter.

An unusually long tuning tube 81 is supported in and spot-welded toflanged necks 83, 85, and 87 of the part-itions 31, 33, and 35, beingspot-welded to the latter two partitions only. The tube 81 isimperforate and connects the crossover chamber 27 4to the chamber 21 andsince it providesthe only inlet and outlet to such chamber it isapparent that this constitutes a resonator chamber for notes of lowfrequency. The chamiber 29 at the outlet end of the mufller is arrangedto act as a resonator chamber by means of a relatively short tuning tube91 which is spot-welded in a flanged neck 93 of the lpartition 37 andone end thereof is preferably spot-welded to the bushing 73.

Coating an assembled mulller, such as the one just described, with aceramic materia-l involves a series of processing steps or operationssuch as the following. First, the muffler is heated to about 1300 F. andheld yfor 5 minutes or so to burn olf grease, soap, oil, etc.After'cooling, the mulller is detergent Washed `by dipping for aboutl0-20 minutes in either or both alkali and acid baths, depending uponthe materials to be removed, and water rinsed after each wash. Next itis held in a pickling lbath, or acid bath, to roughe-n -the surface soas to promote a bond with the ceramic. After this, it is rinsed anddipped in a neutralizing bath and rinsed again. Next it is dipped in anickel lbath to give it a primer coating that promo-testhe bond with theceramic. .Then it is rinsed and neutralized if necessary. After any orall of the various .liquid dipping operations of the type just describedhave been completed (the order may be varied), the muffler may be heldin a tank in which hot dry air is blowing so that il'. can be dried out.

After the foregoing or equivalent preparatory steps are completed andthe muffler surfaces are clean and prepared for ceratmic, the muffler isdipped in a bath 3 of anti-corrosive ceramic slip, drained, dried in hotair, and fired in a furnace at about 1500" F.

It wil-l be recognized that the success of most of the above steps isdependent upon the admission of a lluid to the interior of the mulllerso that it contacts all of the muler surface and then the drainage ofall of such fluid from the interior of the muffler so that the nextfluid can contact all of the muffler surfaces. In the steps involvingliquids (such as detergent washes, rinse-s, pickling, neutralizing, andnickel coating) the muffler is preferably suspended from one end,lowered into a bath containing the liquid, raised out of the bath, anddrained by gravity llow'of the liquid out of the muffler and Iback intothe bath. In mass :production of ceramic coated automobile mulllers itis not only necessary that these various operations be performed we-llbut they must also be performed quickly and automatically without theneed for individual attent-ion and inspection. The effectiveness withwhich the surfaces are contacted by the various fluid and thecompleteness of subsequent drainage as well as the speed with which thefluid enter and leave the mufller all depend upon the use of the propersuspension means and drainage means in the muffler itself. The drainagemeans, however, must not adversely alfect the acoustic characteristicsof the mulller.

Referring rst to the suspension means, this com-prises holes 101 and103, respectively, in the inlet and outlet bushings 39 and 73. Theseholes receive the end 0f a hook '7 or other suitable suspending device.A vertical line from the hole 101 or 103 through the center of gravityof the muffler when suspended determines the angle of inclination of themufller, especially the angle the -various transverse partitions,headers, and walls will -m-ake `to the horizontal. It is evident that inno ease can the muffler be suspended by holes 101 and 103 so that thetransverse walls will be perfectly horizontal. Thus, whether the mullleris suspended from the inlet or the outlet end, each chamber will have alow point t0- ward which liquid in the chamber will flow. In the case ofthe llat interior partitions 31, 33, 35, and 37 these low points willIbe at the corners between the simall di ameter ends of the partitionsand the shell. A-t these corners I provide internal drainage means inthe form of small openings i111 and 113, respectively, which arepreferably about z'/16 inch in diameter and as close as possible to theshell wall. Alternatively, the ends of the partitions could be slicedolf as shown at 114 in FIG. 5A to provide drainage openings. It will benoted that when an opening 111 is on the low side the correspondingopeni-ng 113 `will be on the high side of the adjacent chamber. Thus, asliquid escapes, air can enter to prevent a Vacuum lock in the mufflerduring drainage.

The end headers 15 and 17 of the muffler are provided with externaldrainage means i-n the form of large (preferably 1 inch diameter)openings 104 and 105, respectively, each of which has an outwardlyextending neck 107. These openings .are closed after the coatingoperation is completed by flanged, cup-shaped caps 108 as will bedescribed hereinafter. Additionally, end header -15 may be provided witha 1/16 inch drain hole 106 and header 17 with three such drain holeslocated as shown in FIGS. 3 and 4. More of these holes may be used ifdesired since they are small enough to plug up With ceram-ic during thecoating operation and therefore do not cause adverse acoustic effects.

The spit chambers 57 are provided with internal drainage means in theform of holes 117 and 119 located in diagonally opposite corners, theholes 117 being on the inlet and plug 104 sides of the chambers. Theholes 117 lare preferably about 1A inch in diameter and as close aspossible to the end walls of the chambers 57 so as to eliminate anypockets that might retain liquid during draining.

The coating operation is carried out with the muffler just described,that is, the muffler of FIG. 2 but before the plugs 108 have beeninserted or :the outer layers 9 and |13 added to the shell 11. Duringthe preparatory steps, wherein lthe muffler is dipped in various freeflo'w.

ing liquids as outlined above, the muler is preferably suspended fromthe suspension hole 101 in the inlet bushing 39. The muffler will hangat an angle defined by aline through the hole 101 and the center ofgravity. When this is done ithe holes 104 and 105, respectively, will bevery close to, if not actually, the high and low points of the spaceinside the shell 11. When the mulller -is suspended from the bushing 39and lowered into a liquid bath, the liquid will enter hole and ybushing73 and flow upwardly `toward the inlet header 15. The air replaced bythis liquid can escape externally through openings 104 and 106 in theheader 15 as well as through inlet tube 49 and bushing 39. Air in theinternal charnbers can escape through the uppermost of the variousinternal drainage openings, in this case, the openings -111 and 117.Liquid can enter the internal chambers thnough the various tubes as wellas tlhrough the lower openings 113. After .the muffler is completelysubmerged and held for the desired period of time it will be raised outof .the bath and suspended 4over it so that the liquid will drainout-principally through opening 105. Internally the liquid will drainfrom one chamber to the next through the lower opening 111 and air canenter from the tcp to replace it through the same openings as it flowedthrough to leave the muffler. Liquid in spit chambers 57 will drain intotube 49 through low openings 119. The centrally located hole 106 inheader 17 will provide an outlet for any liquid .tending to form apuddle in the concave portion of the header. The foregoing arrangement'of suspending means and drainage means will enable free flowing liquidto enter and completely leave the muffler without any shaking oragitation, thus facilitating -mass dipping of the mufflers withoutindividual attention Iby an operator.

The ceramic slip 3 is considerably thicker and more viscous than theliquids used in the various preparatory steps and thus flows more slowlythan the other liquids. In order 4to decrease the time required to coatthe muler 1 with ceramic slip, I prefer to suspend it from the outletbushing hole 103 so that it is .oriented more or less as shown in FIG.l. instead of the sma-ller chamber 29 will be on the bottom.

Thus, slip can enter and leave the chamber through large opening 104insteadV of openings l1\11 and 113 and tihe time required to ll anddrain the muer with slip is reduced substantially. After dipping in thebath of slip 3, a hook (not shown) is used to engage bead 20 and pivotthe mufller up about 45 to the left in FIG. l, thus putting the variousdrainage holes at the low points in their respective chambers. Afterdipping in slip 3, the muiers are shaken somewhat by the operators sothat the slip is agitated sufficiently to drain out. This contrasts withthe drainage during the preliminary stepsv which is accomplished withoutshaking of the muffler.

After the muier has been lifted from tank 3 and drained over it, it isdried to remove as many iluids as possible before firing. The dryingmany include a step of subjecting the muffler to circulating hot air (asis done after the preparatory steps) and it will be noted that thelocation of hole 104 on a side opposite tube 81 will preventshort-circuiting such as might occ-ur if the hole were located on theother side of header 15. During firing `of the muffler at an appropriatetemperature, normally about 1500 F., it is preferably suspended by hole101 as this will tend to minimize distortion that might occur due to theheat.

After firing the ceramic is cleaned off the butt ends of necks 107 toexpose metal and plugs 108 are inserted in holes 104 and 105. The plugsare hat-shaped and preferably formed of a non-corrosive, high chromemufer steel. The flanges 109 on the plugs have projections or ribsformed on them to engage the cleaned edges of necks 107. Both plugs areprojection-Welded to the necks in one cycle by simultaneous engagementof both plugs with welding electrodes, the welding current flowing fromthe plug at one end of the muiiler through the muffler shell, which actsas a conductor, to ground or the low potential side by way of the plugat the opposite end of the shell. After this the interiors of the plugsare expanded radially as seen at 110 vto engage behind the headermaterial surrounding :the holes 1104 and y105 and provide a positiveengagement against blow-out.

The ceramic layer will build up on the led-ges of and tend to bridge thevarious holes and reduce them in size. In order to obtain the desiredresults, I prefer to make the various louvers, such as louvers 55 and469, of rec-V tangular shape and about .OBO-.040 oversize .to avoidclogging or bridging.

In FIGS. 8-13 I have illustrated a different method When this is donethe chamber 21 Y of plugging the opening in the header. In this form theopening 150, as shown in FIG. ll, is not anged and would be preferablyabout 1 inch in diameter and arcs 151 extending through approximately aquarter-circle would be slit in the material surrounding .the opening tcform partly annular tabs which would be slit diametrically along line153 and then lifted up from the plane of the header 155 as seen in FIG.l0. The plug 157 willl comprise a flat plate having a rectangular dishedT portion 159 which will receive some type of instrument, such as ascrew driver, so that the plug can be twisted into place. Sections ofthe periphery of the plug are slit and deformed from the plane of theplug surface in a manner complementary to the ears 151 so that, as seenin FIGS. 8-9, the plug can be inserted in the openings and then twistedso that these sections will lie over and under the ears 151 and .theplug will interlock with the header \155. The plug is coated withceramic before insertion so that upon firing a gas-tight seal isobtained.

While, as illustrated, the principles of my invention are shown inconnection with ceramic coating, it is possible `for these features tobe used in the coating of mufflers or other sheet metal devices by othermeans, such as painting or gaseous diffusion, wherever ventilation ofthe interior of the muler may be required during the process.

I claim:

1. A muffler of the type having an elongated casing closed by headermeans and internal gas passages and partition means dividing the casinginto a plurality of chambers, an internal tube having space-d louveredsections, a chamber formed about each of said |louvered sections, and atleast two drainage openings provided in said tube within the confines ofeach chamber to enable ceramic slip or the like when applied internally:to coat all interior parts of the chambers.

2. A mufer of the type having an elongated casing closed by header meansand internal gas passages and partition means dividing the casing into aplurality of chambers, an internal tube having spaced louvered sections,a chamber fonmed about each of said louvered sections, and at least twodrainage openings provided in said tube within the confines of eachchamber, said drainage openings being axially spaced along said tubeclosely adjacent the end walls of said chamber.

3. A muflier of the type having an elongated casing closed by headermeans and internal gas passages and partition means dividing the casinginto a plurality of chambers, an internal tube having spaced louveredsections, a chamber formed about each of said louvered sections, and atleast two drainage openings provided in said ltube within the confinesof each chamber, said drainage openings also being circumferentiallyspaced about said tube.

4. A ceramicv coated muffler ofthe type having a ceramic coatedelongated casing closed by ceramic coated header means and ceramiccoated internal gas passages and ceramic coated partition means dividingthe casing into a plurality of chambers, gas inlet means provided in oneof said header means, gas outlet means provided in vthe other of saidheader means, relatively large drainage opening means formed in saidheader means in spaced relationship to sai-d gas :inlet and outlet meansand said casing to enable ceramic slip or the like to be appliedinternally of said muffler, plug means permanently mounted in said largedrainage opening means permanently sealing said drainage opening meansand providing a substantially continuously closed header meanssurrounding said gas inlet and outlet means, and at least one relativelysmall additional drainage opening provided in said header means adjacentthe casing and spaced :between the casing and the large drainageopenings, said small additional drainage opening being of a sizecloseable by the ceramic coating and being substantially closed by dheceramic slip or the like afier the muffler has been coated internally.

References Cited by the Examiner UNITED STATES PATENTS Dudderar 1811-47Egner 181-72 X Oldberg 181-53 Heath 181-48 X Deremer 181-72 X MacKenzie181-48 Berg et al. 181-54 Long 117-129 Kuhn 181-61 Brightly 181-4-9Hedrich 181-54 Fischer 181-48 X Doughty Bryant 181-57 Powers et al.181-611 Billey 181-53 Muller 181-54 Fetzer et al Kalis 181-72 Powers181-62 X Australia.

RICHARD B. WILKINSON, Primary Examiner.

15 LEO SMILOW, Examiner.

R. S. WARD, Assistant Examiner.

1. A MUFFLER OF THE TYPE HAVING AN ELONGATED CASING CLOSED BY HEADERMEANS AND INTERNAL GAS PASSAGES AND PARTITION MEANS DIVIDING THE CASINGINTO A PLURALITY OF CHAMBERS, AN INTERNAL TUBE HAVING SPACED LOUVEREDSECTIONS, A CHAMBER FORMED ABOUT EACH OF SAID LOUVERED SECTIONS, AND ATLEAST TWO DRAINAGE OPENINGS PROVIDED IN SAID TUBE WITHIN THE CONFINES OFEACH CHAMBER TO ENABLE CERAMIC SLIP OR THE LIKE WHEN APPLIED INTERNALLYTO COAT ALL INTERIOR PARTS OF THE CHAMBERS.